Cellular Telephone Shield for the Reduction of Electromagnetic Radiation Exposure

ABSTRACT

A radiation shield comprises a substrate polymer layer, a conductive layer having an aperture providing access to a front face of a cellular telephone, adjacent the substrate polymer layer, and an adhesion surface adjacent the conductive layer and the front face. A radiation shield comprising a first substrate polymer layer, a conductive layer having an aperture providing access to a touch-sensitive screen of the front face, adjacent the first substrate polymer layer, a second substrate polymer layer adjacent the conductive layer, and an adhesion surface adjacent the conductive layer and the front face. At least one opening provides access to the front face.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application No.61/574,444 filed on Aug. 3, 2011.

FIELD OF THE INVENTION

The field of the invention relates to cellular telephones. Inparticular, the invention relates to the shielding of electromagneticradiation produced by cellular telephones.

BACKGROUND OF THE INVENTION

Wireless devices such as cellular telephones are designed to emitelectromagnetic radiation during use. Repetitive use of these devices,especially in close proximity to the human body, has been postulated toimpart relatively high levels of cumulative radiation. High levels ofexposure have been shown to pose a potential health risk and anincreased risk of certain types of cancers in humans. Increased cancerrisk is of a particular concern, considering the use of cellulartelephones typically occurs close to the head and brain.

When electromagnetic waves are absorbed by an object, the energy of thewaves is converted to heat. Electromagnetic waves can also be reflectedor scattered, in which case their energy is redirected or redistributed.The quantity of radiant energy absorbed transmitted may be calculated byintegrating radiant flux (or power) with respect to time.

Instantaneous electrical power P is given by

P(t)=I(t)·V(t)   [1]

where

-   -   P(t) is the instantaneous power, measured in watts (joules per        second)    -   V(t) is the potential difference (or voltage drop) across the        component, measured in volts    -   I(t) is the current through it, measured in amperes.

In the case of a periodic signal s(t) of period T, like a train ofidentical pulses, the instantaneous power p(t)=|s(t)|² is also aperiodic function of period T. The peak power is defined by:

P ₀=max [p(t)].   [2]

The peak power is not always readily measurable, therefore, and theaverage power is more commonly used as a measure of delivered power. Ifenergy per pulse is defined as:

∈_(pulse)=∫₀ ^(T) p(t)dt   [3]

then the average power is defined as:

$\begin{matrix}{P_{avg} = {{\frac{1}{T}{\int_{0}^{T}{{p(t)}{t}}}} = {\frac{\varepsilon_{pulse}}{T}.}}} & \lbrack 4\rbrack\end{matrix}$

A notable fraction of the power from the electromagnetic radiationemitted by a cellular telephone when in use is absorbed by the humanhead. The electromagnetic radiation emitted by a GSM handset, forexample, has a peak power of about 2 watts. Other digital mobiletechnologies, such as CDMA2000 and D-AMPS, have a peak power of about 1watt.

The specific absorption rate (“SAR”) is the rate at which energy isabsorbed by the body when exposed to a radio frequency electromagneticfield. The SAR level is defined as the power of the electromagneticradiation absorbed per mass of tissue in units of watts per kilogram(W/kg) and is averaged over a small sample volume. SAR maximum levelsfor cellular telephones have been set by governmental regulatingagencies in many countries. In the United States, the FederalCommunications Commission (FCC) has set a SAR limit of 1.6 W/kg,averaged over a volume of l gram of tissue, for the head. In Europe, thelimit is 2 W/kg, averaged over a volume of 10 grams of tissue.

One well-understood effect of electromagnetic radiation is dielectricheating, in which any dielectric material (such as living tissue) isheated by rotations of polar molecules induced by the electromagneticfield. In the case of a person using a cellular telephone, most of theheating effect will occur at the surface of the head, causing itstemperature to increase by a fraction of a degree. In this case, thelevel of temperature increase is an order of magnitude less than thatobtained during the exposure of the head to direct sunlight. The brain'sblood circulation is capable of disposing of excess heat by increasinglocal blood flow. However, other areas of the body, such as the corneaof the eye, do not have this temperature regulation mechanism. Exposureof 2-3 hours duration has been reported to produce cataracts in rabbits'eyes at SAR values from 100-140 W/kg, which produced lenticulartemperatures of 41° C.

Other “non-thermal” effects are less well understood. For example,thermoreceptor molecules in cells activate a variety of secondary andtertiary messenger systems, in order to defend the cell againstmetabolic cell stress caused by heat. The increases in temperature thatcause these changes are too small to be detected by current studies.Further, the communications protocols used by mobile phones often resultin low-frequency pulsing of the carrier signal. Whether thesemodulations have biological significance has been subject to debate.

A study published in 2011 by The Journal of the American MedicalAssociation conducted using fluorodeoxyglucose injections and positronemission tomography concluded that exposure to radiofrequency signalwaves within parts of the brain closest to the cellular telephoneantenna resulted in increased levels of glucose metabolism, but theclinical significance of this finding is unknown.

Despite differing opinions among researchers, evidence has accumulatedthat supports the existence of complex biological effects of weakernon-thermal electromagnetic fields, and modulated RF and microwavefields. The World Health Organization has classified radiofrequencyelectromagnetic radiation as a possible group 2b carcinogen. This groupcontains possible carcinogens with weaker evidence, at the same level ascoffee and automobile exhaust.

At frequencies higher than radio frequencies (e.g., ultraviolet light),the biological effects of radiation are more pronounced. Radiation atthese frequencies has sufficient energy (directly or indirectly) todamage biological molecules through ionization. All frequencies of UVradiation have been classed as Group I carcinogens by the World HealthOrganization. Ultraviolet radiation from sun exposure is the primarycause of skin cancer.

Thus, at UV frequencies and higher, electromagnetic radiation becomesionizing and so does far more damage to biological systems than simpleheating. “Ionization” produces ions and free radicals in materials(including living tissue) with very little heating, resulting in severedamage with little or no warning. Radiation in this frequency range iscurrently considered far more dangerous than the rest of theelectromagnetic spectrum. But, it is postulated that low frequencies,perhaps as low as radio frequencies, can produce ionization effects,like those of X-rays, but at statistically less significant numbers.Over time, the cumulative effects of radio frequency radiation on livingtissue may be significant enough to cause tissue damage.

Radiation exposure may be reduced by decreasing the duration of exposureor increasing the distance between the source of the radiation and thesubject. Alternatively, increasing shielding between the radiationsource and the subject will also reduce radiation exposure.

The prior art has attempted to provide electromagnetic shieldingsolutions for use with cellular telephones but has not been completelysuccessful.

For example, U.S. Pat. No. 7,242,507 to Yen discloses an electromagneticwave absorptive film. The film is comprised of a compound layer and areflective layer. However, the film in Yen requires the embedding ofabsorbing grains into the compound layer leading to a complexmanufacturing process. Further, the film cannot be used on cellulartelephones having touch-sensitive screens.

U.S. Publication No. 2004/0198264 to Saur, et al. discloses a shieldingthat includes a flexible conductive sheet and an adhesive for attachmentto a housing of a wireless telephone. However, the shielding apparatusdisclosed in Saur cannot be used with cellular telephones havingtouch-sensitive screens.

PCT Publication No. WO 2010/115159 to Bradshaw, et al. discloses metalnanopowders for use as radiation shields. However, to be effective thenanoparticles and nanopowders in Bradshaw require two layers, a core andan outer layer. Further, the outer layer requires a group of severalorganic substituents, which require a complicated and labor intensivemanufacturing process.

The prior art fails to disclose or suggest a radiation shield for ahandheld cellular telephone having a simple construction and a widerange of uses including uses with touch-sensitive screens. Therefore,there is a need in the art for a radiation shield for cellulartelephones such as cellular telephones that is easy to manufacture andadaptable for use on a wide range of cellular telephones, includingdevices with touch-sensitive screens.

SUMMARY

In one embodiment, a radiation shield for attachment to a cellulartelephone having a front face and a set of controls comprises asubstrate polymer layer, a conductive layer having an aperture, adjacentthe substrate polymer layer, and an adhesion surface adjacent theconductive layer and the front face. The radiation shield has at leastone opening providing access to the set of controls. The apertureprovides access to the front face.

In another embodiment, the radiation shield comprises a first substratepolymer layer, a conductive layer having an aperture, adjacent the firstsubstrate polymer layer, a second substrate polymer layer adjacent theconductive layer, and an adhesion surface adjacent the conductive layerand the front face. The radiation shield has at least one openingproviding access to the set of controls. The aperture provides access toa touch-sensitive screen of the front face.

In another embodiment, a cellular telephone having a touch-sensitivescreen comprises a base having a set of controls, a radiation shieldhaving at least one opening providing access to the set of controls,adjacent the base, and a cover adjacent the radiation shield andattached to the base. The radiation shield further comprises a firstsubstrate polymer layer, a conductive layer having an aperture providingaccess to the touch-sensitive screen, adjacent the first substratepolymer layer, and a second substrate polymer layer adjacent theconductive layer. The radiation shield has at least one openingproviding access to the set of controls. The aperture provides access tothe touch-sensitive screen.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed embodiments will be described with reference to theaccompanying drawings.

FIG. 1 is an exploded isometric view of a preferred embodiment.

FIG. 2 is an exploded isometric view of a preferred embodiment.

FIG. 3 is an isometric view of a preferred embodiment in use.

FIG. 4 is an isometric view of a preferred embodiment in use.

FIG. 5 is an exploded isometric view of a preferred embodiment in use.

FIG. 6 is a plot of an electromagnetic radiation pattern in a curvedplane produced by a cellular telephone.

FIG. 7 is a plot of an electromagnetic radiation pattern in a curvedplane produced by a cellular telephone utilizing a preferred embodiment.

FIG. 8 is an isometric view of a cellular telephone.

FIG. 9A is a graph of an electromagnetic radiation pattern measured froma cellular telephone and a cellular telephone utilizing a preferredembodiment along an x-axis.

FIG. 9B is a graph of an electromagnetic radiation pattern measured froma cellular telephone of the prior art and a cellular telephone utilizinga preferred embodiment along a y-axis.

FIG. 9C is a graph of an electromagnetic radiation pattern measured froma cellular telephone of the prior art and a cellular telephone utilizinga preferred embodiment along a z-axis.

DETAILED DESCRIPTION

Referring to FIG. 1, radiation shield 100 comprises a substrate polymerlayer 101, a scratch resistant layer 104, conductive layer 102, andadhesive layer 103, polymer layer 101, opening 107, and opening 108.Conductive layer 102 has apertures 109, 110 and 111. Adhesive layer 103has attachment surface 105, tack surface 106, opening 112, and opening113.

In a preferred embodiment, substrate polymer layer 101 is comprised of apolyester substrate having a thickness of between about 0.01 mm and 0.02mm.

In a preferred embodiment, substrate polymer layer 101 is comprised ofpolyethylene terephthalate (“PET”) having a thickness of between about0.5 mm and 1.0 mm.

In a preferred embodiment, substrate polymer layer 101 is a glassmaterial having a thickness of between about 0.5 millimeters and 1.0millimeters. Preferred glasses include 75% silica glass havingnon-metallic doping.

In another embodiment, substrate polymer layer 101 is comprised of apolycarbonate material having a thickness of between about 0.5millimeters and 1.0 millimeters. Preferred polycarbonate materials areLEXAN®, MAKROKOM® or MAKROCLEAN® available from Sabic InnovativePlastics and Aria Plast AB of Sweden, respectively.

In a preferred embodiment, scratch resistant layer 104 is a scratchresistant material having a thickness of between about 0.01 millimetersand 0.02 millimeters. In a preferred embodiment, the scratch resistantsurface is an acrylic coating or magnesium fluoride applied by sprayingduring manufacture.

In a preferred embodiment, conductive layer 102 is a metallic coatingwhich is applied to the substrate polymer, having a thickness of betweenapproximately 0.03 millimeters and 0.06 millimeters and a sheetresistance of between about 10 ohms per square and about 15 ohms persquare. Preferred methods of manufacture include sputtering and vapordeposition of the metallic layer onto the substrate polymer. Apertures109 and 111 do not have conductive layer 102. In a preferred embodiment,the substrate polymer is masked during application of the conductivelayer to create apertures 109, 110 and 111. The apertures provideseveral functions. First, they allow the “touch-sensitive” screen ofmodern cellphones to function. Second, they provide sufficientvisibility to all the cellular telephone display to be seen. Also, thepartial metal coating remaining after etching provides additionalelectromagnetic shielding properties. In other embodiments, theconductive layer is removed after deposition by laser or chemicaletching, particularly hydrochloric acid or nitric acid. Conductive layer102 is preferably comprised of indium tin oxide having a transparency ofat least 84% light transmission upon application. Other conductivematerials such as silver, gold, and carbon nanotubes or graphene willalso suffice. Conductive polymers can also be used with success, such aspolyacetylene, polyphenylenen vinylene, polythophene and polyphylenesulfide. Similarly, conducting polymer nanofibers can be used withsuccess, particularly polyaniline nanofibers and carbon nanofibers.

In a preferred embodiment, adhesive layer 103 is a transparent adhesivehaving a thickness of between about 0.035 and 0.065 millimeters.Ideally, the adhesive coating adheres permanently to conductive layer102, but enables tack surface 106 to be removed and repositioned onsurfaces of a cellular telephone. In a preferred embodiment, theadhesive is No. 7651 adhesive available from Dow Corning Corporation ofMidland, Mich., has an adhesive strength range of approximately 1.97grams per meter (g/m) to approximately 3.94 grams per meter (g/m). Otheradhesives with suitable transparent properties will also suffice.

In another embodiment, adhesive layer 103 comprises a polymer coatingsuitable for static adherence to the face of a cellular telephone.

Referring to FIG. 2, an alternative embodiment is shown. Radiationshield 200 comprises scratch resistant layer 205, first substratepolymer layer 201, conductive layer 202, second substrate polymer layer203, and adhesive layer 204. First substrate polymer layer 201 hasopenings 208, 209, and 210. Conductive layer 202 attaches to firstsubstrate polymer layer 201. Conductive layer 202 has openings 211, 212,and 213, and aperture 214. Second polymer layer 203 attaches toconductive layer 202. Second substrate polymer layer 203 has openings215, 216, and 217. Adhesive layer 204 attaches to second substratepolymer layer 203. Adhesive layer 204 has attachment surface 206, tacksurface 207, and openings 218, 219, and 220.

In a preferred embodiment, scratch resistant layer 205 is a magnesiumfluoride coating of between about 0.01 millimeters and 0.015millimeters, applied through vapor deposition.

In a preferred embodiment, first substrate polymer layer 201 is made ofa polyester substrate having a thickness of between about 0.1millimeters and 0.7 millimeters.

[00491 In a preferred embodiment, first substrate polymer layer 201 iscomprised of polyethylene terephthalate (“PET”) having a thickness ofbetween about 0.1 mm and 0.7 mm.

In another embodiment, first substrate polymer layer 201 is made of aglass material having a thickness of between about 0.1 millimeters and0.7 millimeters. Preferred glasses include 75% silica glass havingnon-metallic doping.

In another embodiment, first substrate polymer layer 201 is made of apolycarbonate material having a thickness of between about 0.1millimeters and 0.7 millimeters. Preferred polycarbonates are LEXAN®,MAKROKOM® or MAKROCLEAN® available from Sabic Innovative Plastics andAria Plast AB of Sweden, respectively.

In a preferred embodiment, second substrate polymer layer 203 has athickness of between about 0.1 millimeters and 0.7 millimeters.

In a preferred embodiment, second polymer layer 203 is made of apolyester substrate having a thickness of between about 0.1 millimetersand 0.7 millimeters.

In a preferred embodiment, second substrate polymer layer 203 iscomprised of polyethylene terephthalate (“PET”) having a thickness ofbetween about 0.1 mm and 0.7 mm.

In another embodiment, second substrate polymer layer 203 is made of aglass material having a thickness of between about 0.25 millimeters and0.5 millimeters. Preferred glasses include 75% silica glass havingnon-metallic doping.

In another embodiment, second substrate polymer layer 203 is made of apolycarbonate material having a thickness of between about 0.1millimeters and 0.7 millimeters. Preferred polycarbonates are LEXAN®,MAKROKOM® or MAKROCLEAN® available from Sabic Innovative Plastics andAria Plast AB of Sweden, respectively.

In a preferred embodiment, conductive layer 202 is a metallic coatingwhich is applied to the substrate polymer, having a thickness of betweenapproximately 0.03 millimeters and 0.06 millimeters and a sheetresistance of between about 10 ohms per square and about 15 ohms persquare. Preferred methods of manufacture include sputtering and vapordeposition of the metallic layer onto the substrate polymer. Openings211, 212, 213 and aperture 214 do not have conductive layer 202. In apreferred embodiment, the substrate polymer is masked during applicationof the conductive layer to create openings 211, 212, 213 and aperture214. In other embodiments, the conductive layer is removed afterdeposition by laser or chemical etching, particularly hydrochloric acidor nitric acid. Conductive layer 202 is preferably comprised of indiumtin oxide having a transparency of at least 84% light transmission uponapplication. Other conductive materials such as silver, gold, and carbonnanotubes or graphene will also suffice. Conductive polymers can also beused with success, such as polyacetylene, polyphenylenen vinylene,polythophene and polyphylene sulfide. Similarly, conducting polymernanofibers can be used with success, particularly polyaniline nanofibersand carbon nanofibers.

In a preferred embodiment, adhesive layer 204 is a transparent adhesivehaving a thickness of approximately 0.035 and 0.065 millimeters andproperties that enable it to permanently adhere to second polymer layer203 and yet enable tack surface 207 to removably attach to flat surfaceson a cellular telephone. In a preferred embodiment, the adhesive is No.7651 adhesive available from Dow Corning Corporation of Midland, Mich.,has an adhesive strength range of approximately 1.97 grams per meter(g/m) to approximately 3.94 grams per meter (g/m). Other adhesives withsuitably transparent properties will also suffice.

Referring to FIG. 3, an application of an assembled radiation shield toa cellular telephone is shown. Radiation shield 301 has aperture 302,openings 303 and 304. The shield includes exposed scratch resistantsurface 305 and exposed tack surface 306. Exemplary cellular telephone401 has front surface 402, speaker 403, screen 404, trackball 405, andkeyboard 406. Opening 303 approximately matches speaker 403. Opening 304approximately matches the dimensions of keyboard 406 and trackball 405.Aperture 302 has a set of dimensions sized to approximately match thedimensions of screen 404.

In the assembled radiation shield 301 includes aperture 302. Aperture302 is an area of the shield where conductive layer 307 is not present.In this embodiment, openings 303 and 304 extend through radiation shield301. Aperture 302 allows screen 404 to properly function. Aperture 302is largely transparent due to the transparency of the substratepolycarbonate layer and the scratch resistant layer. The transparencyallows transmission of the light from the screen of the cellulartelephone. Opening 304 allows controls of the cellular telephone to beeasily accessed. Similarly, opening 303 allows sound from the speaker toexit the phone unhindered.

In a preferred embodiment, tack surface 306 is adhered to front surface402 by static attraction.

Referring to FIG. 4, another embodiment is shown. Radiation shield 350includes aperture 351, openings 352, 353, and 354, scratch resistantsurface 355, tack surface 356, and conductive layer 357. Cellulartelephone 451 has front outside surface 452, speaker 453, camera 454,touch-sensitive screen 455, and button 456. Aperture 351 has a set ofdimensions that are approximately equal to the dimensions oftouch-sensitive screen 455. Opening 352 is sized to approximately matchspeaker 453. Opening 353 is sized to approximately match camera 454.Opening 354 is sized to approximately match button 456.

In the assembled radiation shield 350 includes aperture 351. Aperture351 is an area of the shield where conductive layer 357 is not present.In this embodiment, openings 352, 353 and 354 extend through radiationshield 350. Aperture 351 allows touch-sensitive screen 455 to maintaintouch-sensitive functionality. Aperture 351 is largely transparent dueto the transparency of the substrate polycarbonate layer and the scratchresistant layer. The transparently allows transmission of the light fromthe screen of the cellular telephone. Opening 303 allows controls of thecellular telephone to be easily accessed. Similarly, opening 352 allowssound from the speaker to exit the phone unhindered.

In a preferred embodiment, tack surface 356 is adhered to front surface452 by static attraction.

Referring to FIG. 5, another embodiment is shown. In this embodiment,radiation shield 350 is shown positioned inside a cellular telephoneassembly. In this embodiment, radiation shield 350 has the same layeredconstruction as radiation shield 200 of FIG. 2, except radiation shield350 does not include adhesive layer 204 or scratch resistant layer 205.Cellular telephone 451 includes base 461 and cover 462. Base 461includes speaker 453, camera 454, screen 455, and button 456. Cover 462includes front outside surface 452 and front inside surface 464.Radiation shield 350 is located inside cellular telephone 451 betweenbase 461 and cover 462, and adjacent front inside surface 464.

Tests were conducted to measure the specific absorption rate produced bythree cellular telephones with and without the radiation shield at alocation on a simulated human head. In the following tests, the samplevolume is 1 gram of tissue.

The detection system used in each test was a DASY52 dosimetric scannermanufactured and sold by Schmid & Partner Engineering AG of Zurich,Switzerland (“SPEAG”) having an EX3DV3 probe attached to the DASY52scanner. The simulated human head called a “phantom” was a SAM2 phantommanufactured and sold by SPEAG. The sensor position was sweptrobotically through multiple positions within the phantom to measure theelectromagnetic radiation produced by the cellular telephone.

Test 1 Results

FIG. 6 shows a map of radiated power as measured in the matching fluid.Cellular telephone 10 was positioned in contact with surface 11 at aperpendicular tangent at electromagnetic radiation source 25 on surface11. Equipotential lines 12, 13, and 14 of the electromagnetic radiationare mapped on surface 11. The cellular device emitted approximately two(2) watts peak power. Equipotential lines 12, 13, and 14 have values ofapproximately 0.783 mW/g, 0.626 mW/g, and 0.470 mW/g, respectively.Equipotential lines 12, 13, and 14 appear as radial distances fromelectromagnetic radiation source 25 of approximately 1.5, 2.5, and 2.8centimeters, respectively.

Referring to FIG. 7, radiation shield 15 is shown attached to cellulartelephone 10. Equipotential lines 16, 17, and 18 are mapped on surface11 when cellular telephone with radiation shield 15 is use.Equipotential lines 16, 17, and 18 have values of approximately 0.697mW/g, 0.559 mW/g, and 0.457 mW/g, respectively. Equipotential lines 16,17, and 18 appear as radial distances from electromagnetic radiationsource 25 of approximately 1.5, 2.8, and 3.0 centimeters, respectively.

Comparing FIGS. 6 and 7, it is seen that the radiation shield 15attenuates the electromagnetic radiation directed toward the human headfrom a cellular telephone 10. Equipotential lines 16, 17, and 18 areattenuated by as much as 30% when compared to equipotential lines 12,13, and 14 in distance. As a result, radiation levels are reduced acrosssurface 11 thereby reducing radiation absorbed by the human tissue.

Test 2 Results

Test 2 measured the SAR level produced by the Apple® iPhone 4 cellulartelephone positioned against the right-hand side of the simulated humanhead. Three SAR levels were tested: a baseline SAR level produced withno radiation shielding attached; a SAR level produced with radiationshield 200 attached to the phone; and a SAR level produced with aportion of the lower section removed.

The results of Test 2 are listed in Table 1 below.

TABLE 1 Apple ® iPhone 4 SAR Measurement Results SAR Frequency Side of 1g Device Band Channel (MHz) Mode Head (W/kg) iPhone 4 Cell 189 836.60GSM Right 0.823 (baseline) Voice iPhone 4 with Cell 189 836.60 GSM Right0.134 Radiation Shield Voice iPhone 4 with Cell 189 836.60 GSM Right0.712 Radiation Shield Voice with lower section removed to exposecellular antenna

Test 3 Results

Test 3 measured the SAR level produced by the Apple® iPhone 3 cellulartelephone positioned against the right-hand side ear and the left-handside ear of the simulated human head. Eight SAR levels produced by theApple® iPhone 3 cellular telephone were measured, with and without theradiation shield attached to the cellular telephone: four SAR levelswith the cellular telephone operating in the 800 MHz band; and four SARlevels with the cellular telephone operating in the 1900 MHz PCS band. Abaseline SAR level was measured from the phone with no radiationshielding attached.

The results of Test 3 are listed in Table 2 below.

TABLE 2 Apple ® iPhone 3 SAR Measurement Results SAR Frequency Side of 1g Device Band Channel (MHz) Mode Head (W/kg) iPhone 3 Cell 189 836.60GSM Right 0.418 (baseline) Voice iPhone 3 with Cell 189 836.60 GSM Right0.311 Radiation Shield Voice iPhone 3 Cell 189 836.60 GSM Left 0.371(baseline) Voice iPhone 3 with Cell 189 836.60 GSM Left 0.314 RadiationShield Voice iPhone 3 PCS 661 1880.0 GSM Right 1.250 (baseline) VoiceiPhone 3 with PCS 661 1880.0 GSM Right 0.307 Radiation Shield VoiceiPhone 3 PCS 661 1880.0 GSM Left 0.997 (baseline) Voice iPhone 3 withPCS 661 1880.0 GSM Left 0.290 Radiation Shield Voice

Test 4 Results

Test 4 measured the SAR level produced by the HTC® Evo cellulartelephone positioned against the right-hand side ear and the left-handside ear of the simulated human head. Eight SAR levels produced by thephone were measured, with and without an embodiment of the radiationshield disclosed herein attached to the phone: four SAR levels with thephone operating in the 800 MHz band; and four SAR levels with the phoneoperating in the 1900 MHz PCS band. A baseline SAR level was measuredfrom the phone operating with no radiation shielding attached, at eachhead band of operation.

The results of Test 4 are listed in Table 3 below.

TABLE 3 HTC ® Evo SAR Measurement Results Fre- Side SAR quency of 1 gDevice Band Channel (MHz) Mode Head (W/kg) HTC ® Evo Cell 384 836.52CDMA- Right 0.737 (baseline) RC3/SO55 HTC ® Evo with Cell 384 836.52CDMA- Right 0.659 Radiation Shield RC3/SO55 HTC ® Evo Cell 384 836.52CDMA- Left 0.900 (baseline) RC3/SO55 HTC ® Evo with Cell 384 836.52CDMA- Left 0.816 Radiation Shield RC3/SO55 HTC ® Evo PCS 600 1880.0CDMA- Right 1.620 (baseline) RC3/SO55 HTC ® Evo with PCS 600 1880.0CDMA- Right 0.989 Radiation Shield RC3/SO55 HTC ® Evo PCS 600 1880.0CDMA- Left 1.800 (baseline) RC3/SO55 HTC ® Evo with PCS 600 1880.0 CDMA-Left 1.170 Radiation Shield RC3/SO55

Referring to FIGS. 8, 9A-9C, components of the electromagnetic poweremitted by a cellular telephone with and without a radiation shieldpresent are plotted x-axis 30, y-axis 21 and z-axis 22 related to acellular phone body. Cellular telephone 10 has surface 23 andelectromagnetic radiation source 25. X-axis 30 extends parallel tosurface 23, through electromagnetic radiation source 25. Y-axis 21extends parallel to surface 23, through electromagnetic radiation source25 and parallel to height 24. Z-axis 22 extends perpendicular to bothy-axis 21 and x-axis 30 and perpendicularly from surface 23 throughelectromagnetic radiation source 25.

Referring to FIG. 9A, curve 81 shows the power, measured in milliWatts(mW), at distances along x-axis 30 from electromagnetic radiation source25 with no radiation shielding. Curve 85 shows the power in mW atdistances along x-axis 30 from electromagnetic radiation source 25 withradiation shield 15 attached to cellular telephone 10.

Curve 85 shows the power, measured in milliWatts (mW), at distancesalong the x-axis from electromagnetic radiation source 25 with radiationshield 15 adhered to the surface of electromagnetic radiation source 25.The power is significantly less than the power measured with noradiation shield. Point 80 shows a peak power of approximately 0.780 mW.Point 83 shows a power of approximately 0.157 mW. Point 84 shows a peakpower of approximately 0.697 mW. Point 86 shows a power of approximately0.152 mW.

Referring to FIG. 9B, curve 88 shows the power, measured in milliWatts(mW), at distances along y-axis 21 from electromagnetic radiation source25 with no radiation shielding. Curve 91 shows the power in mW atdistances along y-axis 21 from electromagnetic radiation source 25 withradiation shield 15 attached to cellular telephone 10.

Curve 91 shows the power, measured in milliWatts (mW), at distancesalong the y-axis from electromagnetic radiation source 25 with radiationshield 15 adhered to the surface of electromagnetic radiation source 25.The power is significantly less than the power measured with noradiation shield. Point 87 shows a peak power of approximately 0.780 mW.Point 89 shows a power of approximately 0.157 mW. Point 90 shows a peakpower of approximately 0.697 mW. Point 92 shows a power of approximately0.152 mW.

Referring to FIG. 9C, curve 94 shows the power, measured in milliWatts(mW), at distances along z-axis 22 from electromagnetic radiation source25 with no radiation shielding. Curve 97 shows the power in mW atdistances along z-axis 22 from electromagnetic radiation source 25 withradiation shield 15 attached to cellular telephone 10.

Curve 97 shows the power, measured in milliWatts (mW), at distancesalong the x-axis from electromagnetic radiation source 25 with radiationshield 15 adhered to the surface of electromagnetic radiation source 25.The power is significantly less than the power measured with noradiation shield. Point 93 shows a peak power of approximately 0.780 mW.Point 95 shows a power of approximately 0.157 mW. Point 96 shows a peakpower of approximately 0.697 mW. Point 98 shows a power of approximately0.152 mW.

It will be appreciated by those skilled in the art that modificationscan be made to the embodiments disclosed and remain within the inventiveconcept. Therefore, this invention is not limited to the specificembodiments disclosed, but is intended to cover changes within the scopeand spirit of the claims.

1. A radiation shield for attachment to a cellular telephone, thecellular telephone having a front face and a set of controls,comprising: a substrate polymer layer; a conductive layer having anaperture providing access to the front face, adjacent the substratepolymer layer; an adhesion surface, adjacent the conductive layer andthe front face; the radiation shield having at least one openingadjacent to the set of controls; whereby the radiation shield attenuateselectromagnetic radiation.
 2. The radiation shield of claim 1, whereinthe aperture further comprises a semi-transparent region having at least84% transparency.
 3. The radiation shield of claim 1, wherein theconductive layer is further comprised of a material selected from thegroup of indium tin oxide, silver, gold, graphene, carbon nanotubes,polyacetylene, polyphenylenen vinylene, polythophene, polyphylenesulfide, polyaniline nanofibers, and carbon nanofibers.
 4. The radiationshield of claim 1, wherein the conductive layer has a sheet resistancerange of about 10 ohms per square to about 15 ohms per square.
 5. Theradiation shield of claim 1, wherein the conductive layer has athickness range of approximately 0.03 mm to approximately 0.06 mm. 6.The radiation shield of claim 1, wherein the substrate polymer layer hasa thickness range of approximately 0.5 mm to approximately 1.0 mm. 7.The radiation shield of claim 1, wherein the substrate polymer layer isa material selected from the group of polyester, polyethyleneterephthalate, glass, and polycarbonate.
 8. The radiation shield ofclaim 2, wherein the adhesive layer has a thickness range ofapproximately 0.035 mm to approximately 0.065 mm.
 9. The radiationshield of claim 2, wherein the adhesive layer is a 7651 transparentadhesive product.
 10. A radiation shield for attachment to a cellulartelephone, the cellular telephone having a front face and atouch-sensitive screen, comprising: a first substrate polymer layer; aconductive layer, adjacent the first substrate polymer layer; a secondsubstrate polymer layer, adjacent the conductive layer; an adhesionsurface, adjacent the second substrate polymer layer and the front face;the conductive layer having an aperture adjacent the touch-sensitivescreen; whereby the radiation shield attenuates electromagneticradiation.
 11. The radiation shield of claim 10, wherein the cellulartelephone has a set of controls and the radiation shield has at leastone opening providing access to the set of controls.
 12. The radiationshield of claim 10, wherein the first substrate polymer layer has athickness range of approximately 0.1 mm to approximately 0.7 mm.
 13. Theradiation shield of claim 10, wherein the first substrate polymer layeris a material selected from the group of polyester, polyethyleneterephthalate, glass, and polycarbonate.
 14. The radiation shield ofclaim 10, wherein the second substrate polymer layer has a thicknessrange of approximately 0.1 mm to approximately 0.7 mm.
 15. The radiationshield of claim 10, wherein the second substrate polymer layer is amaterial selected from the group of polyester, polyethyleneterephthalate, glass, and polycarbonate.
 16. The radiation shield ofclaim 10, wherein the conductive layer has a sheet resistance range ofabout 10 ohms per square to about 15 ohms per square.
 17. The radiationshield of claim 10, wherein the conductive layer has a thickness rangeof approximately 0.03 mm to approximately 0.06 mm.
 18. The radiationshield of claim 10, wherein the conductive layer is made of a materialselected from the group of indium tin oxide, silver, gold, graphene,carbon nanotubes, polyacetylene, polyphenylenen vinylene, polythophene,polyphylene sulfide, polyaniline nanofibers, and carbon nanofibers. 19.The radiation shield of claim 10, wherein the adhesion surface furthercomprises an adhesive layer.
 20. The radiation shield of claim 10,wherein the adhesive layer has a thickness range of approximately 0.035mm to approximately 0.065 mm.
 21. The radiation shield of claim 10,wherein the aperture is a semi-transparent region having at least 84%transparency.
 22. A cellular telephone having a touch-sensitive screen,comprising: a base having a set of controls; a radiation shield,adjacent the base, having at least one opening adjacent the set ofcontrols; a cover adjacent the radiation shield and attached to thebase; the radiation shield further comprising: a first substrate polymerlayer; a conductive layer having an aperture adjacent thetouch-sensitive screen and adjacent the first substrate layer; andwhereby the radiation shield reduces a transmission of electromagneticradiation.
 23. The cellular telephone of claim 22, wherein the firstsubstrate polymer layer has a thickness range of approximately 0.1 mm toapproximately 0.7 mm.
 24. The cellular telephone of claim 22, whereinthe first substrate polymer layer is a material selected from the groupof polyester, polyethylene terephthalate, glass, and polycarbonate. 25.The cellular telephone of claim 22, wherein the conductive layer has asheet resistance range of about 10 ohms per square to about 15 ohms persquare.
 26. The cellular telephone of claim 22, wherein the conductivelayer has a thickness range of approximately 0.03 mm to approximately0.06 mm.
 27. The cellular telephone of claim 22, wherein the conductivelayer is made of a material selected from the group of indium tin oxide,silver, gold, graphene, carbon nanotubes, polyacetylene, polyphenylenenvinylene, polythophene, polyphylene sulfide, polyaniline nanofibers, andcarbon nanofibers.
 28. The cellular telephone of claim 22, wherein theradiation shield further comprises: a second polymer layer adjacent theconductive layer and adjacent the touch-sensitive screen; and whereinthe aperture provides access to the touch-sensitive screen.
 29. Thecellular telephone of claim 28, wherein the second substrate polymerlayer has a thickness range of approximately 0.1 mm to approximately 0.7mm.
 30. The cellular telephone of claim 28, wherein the second substratepolymer layer is a material selected from the group of polyester,polyethylene terephthalate, glass, and polycarbonate.
 31. A method forreducing an electromagnetic radiation level produced by a cellulartelephone utilizing a radiation shield comprising a substrate polymerlayer; a conductive layer having an aperture, adjacent the substratepolymer layer; and an adhesive layer adjacent the conductive layer; themethod comprising the steps of: removably attaching the radiation shieldto the cellular telephone; and operating the cellular telephone.
 32. Themethod of claim 31, wherein the step of operating the cellular telephonefurther comprises the step of operating the cellular telephone throughthe aperture.
 33. The method of claim 31, wherein the step of removablyattaching the radiation shield to the cellular telephone furthercomprises the step of removably attaching the radiation shield to afront face of the cellular telephone.
 34. The method of claim 31,further comprising an initial step of providing a material for theconductive layer selected from the group indium tin oxide, silver, gold,graphene, carbon nanotubes, polyacetylene, polyphenylenen vinylene,polythophene, polyphylene sulfide, polyaniline nanofibers, and carbonnanofibers.
 35. The method of claim 31, further comprising an initialstep of providing a sheet resistance range of about 10 ohms per squareto about 15 ohms per square.